Comparison between using CCFs, CCF metrics (FWHM, bisector, contrast), and activity indexes (s-index, Ca ii, NaD, H_α) as activity correction models for the Old DRS (3.7). On the bottom panel, the corrected scatter metrics (σ_ac, σ_us) for each of the activity models are plotted. The activity corrected standard deviation σ_ac measures the scatter in the activity corrected RV measurements. The unexplained scatter (σ_us) measures the scatter remaining after removing all known contributions (stellar activity, planet signal, estimated instrumental noise, photon noise) to the RV signal. These scatter metrics are defined in more detail in subsection 3.5. In the top panel, we include the estimated semi-amplitude of K2-167 b for each activity correction model and the corresponding error bars and detection significance to check how well the planet signal is preserved for each activity mitigation method.